   percentages are out of 100"
   [{storage :storage} feature-name percent]
   (update-in-storage
+    feature-name
     (fn [feature]
       (assoc feature
              :percentage

  "activate a feature for a particular user"
  [{storage :storage} feature-name user]
  (update-in-storage
    (fn [feature]
      (update-in feature
                :users

  A group is just a string"
  [{storage :storage} feature-name group]
  (update-in-storage
    feature-name
    (fn [feature]
      (update-in feature
                 :groups
